The cleanup of acid gasses or sour gas, such as CO2 in particular, from natural gas and in oil refining has been an extensively practiced technology. The industrial removal of CO2 from natural gas dates back to the 1930's. In the 21st century, due to the potential impact of anthropogenic CO2 emissions on the climate, post-combustion CO2 capture has gained tremendous attention. While several technologies exist for the removal of acid gasses one of the most commonly employed practices is the use of aqueous amines. Of these amines, tertiary amines are often used for natural gas applications due to their low energy of regeneration. For post-combustion CO2 capture applications primary and secondary amines tend to be in part favored by their faster rate at the low CO2 driving force condition. Regardless of the application, the mass transfer rate in the absorber column dictates the size of the column (capital cost) used and, consequently, has a substantial impact on the overall process cost. An overall process depicting a thermal swing process is presented in FIG. 1. An aqueous amine solution is circulated between the absorber 10 and stripper 12. The gas, containing CO2, enters the bottom of the absorber where it contacts the aqueous amine absorbent removing it from the gas stream. The liquid solution, CO2 rich amine solution, is then passed through a heat exchanger 14 to improve efficiency before being heated to a higher temperature in the stripper 12. The stripper 12 removes the CO2 as a gas from the amine solution to produce a lean, or CO2 deficient solution. The lean solution is returned to the absorber 10 by way of the heat exchanger 14 to repeat the process.
In order to minimize system capital (absorber cost) it is important to maximize the overall mass transfer rate for the scrubber system as there is a direct correlation between the two. This invention relates to methods for this purpose as well as to catalyst compounds useful in those methods.